A class of Ga-Al-P-based compounds with disordered lattice as advanced anode materials for Li-ion batteries

Abstract

Phosphides possess large reversible capacity, small voltage hysteresis, and high energy efficiency, thus promising to be new anode candidates to replace commercial graphite for Li-ion batteries (LIBs). Through a facile mechanochemistry method, we prepare a novel ternary phosphide of Ga0.5Al0.5P whose crystalline structure is determined to be a cation-disordered cubic zinc sulfide structure according to XRD refinement. As an anode for LIBs, the Ga0.5Al0.5P delivers a reversible capacity of 1,352 mA h g−1 at 100 mA g−1 with an initial Coulombic efficiency (ICE) up to 90.0% based on a reversible Li-storage mechanism integrating intercalation and subsequent conversion processes as confirmed by various characterizations techniques including in-situ XRD, ex-situ Raman, and XPS and electrochemical characterizations. Graphite-modified Ga0.5Al0.5P exhibits a long-lasting cycling stability of retaining 1,182 mA h g−1 after 300 cycles at 100 mA g−1, and 625 mA h g−1 after 800 cycles at 2,000 mA g−1, and a high-rate performance of remaining 342 mA h g−1 at 20,000 mA g−1. The outstanding electrochemical performances can be attributed to enhanced reaction kinetics enabled by the capacitive behaviors and the faster Li-ion diffusion enabled by the cation-mixing. Importantly, by tuning the cationic ratio, we develop a novel series of cation-mixed compounds of Ga1/3Al2/3P, Ga1/4Al3/4P, Ga1/5Al4/5P, Ga2/3Al1/3P, Ga3/4Al1/4P, and Ga4/5Al1/5P, which demonstrate large capacity, high ICE, and suitable anode potentials. Broadly, these compounds with disordered lattices probably present novel physicochemical properties, and high electrochemical performances, thus providing a new perspective for new materials design.